Hydrogen fuel cell exhaust system

ABSTRACT

The present invention is a hydrogen exhaust device for fuel cell. A tail gas discharge device for a fuel cell system includes a steam trap, a buffer solenoid valve, a buffer tank and a drain solenoid valve. The steam trap can collect water from wet hydrogen. The buffer tank is a hollow cavity structure such as a tank. Preferably, the steam trap has an upper cover, a main body, a lower cover and a filter. The upper cover has a wet hydrogen inlet, a pressure sensor, a dry hydrogen outlet and a temperature sensor. The lower cover has a liquid storage cavity and a filter support part. The filter has a filter filler and a filter intake channel.

PROPOSED CLASS

Y02E 60/30 Hydrogen Technology

FIELD OF THE INVENTION

The present invention is in the field of hydrogen fuel cell exhaustsystems.

DISCUSSION OF RELATED ART

One of the most important recent developments in sustainable energyvehicle design is fuel-cell vehicles. A variety of different operatingconditions such as hydrothermal management, hydrogen pressurefluctuation, metering ratio, drainage and exhaust are important factorsthat affect the performance and reliability of the fuel cell system.Presently, the main method to solve the problem of drainage and exhauston the hydrogen side and the metering ratio is by increasing thehydrogen side circulation and adding a hydrophobic device on thecirculation side. Also, adding a valve at the hydrogen outlet allowsexhaust of hydrogen directly to the atmosphere, however thisintermittent opening of a hydrogen outlet creates pressure fluctuationswhen the drainage and exhaust valves are opened, especially under-powerand high-pressure operations. This affects the electrical performanceand reliability of the fuel-cell system. The current state of thehydrophobic device design is inefficient. For fuel-cell systems withdifferent power levels, the filters often need to be recalibrated.Therefore, an efficient hydrogen exhaust device is needed for optimizingfuel-cell operation.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a hydrogen exhaustdevice that buffers both drainage and exhaust, reduces the impact ofsystem pressure fluctuations on the hydrogen side, and increaseselectrical performance and system reliability while providing animproved integration and expansion performance for use on a fuel-cellsystem that has multiple power levels.

The present invention is a hydrogen exhaust device for fuel cell. A tailgas discharge device for a fuel cell system includes a steam trap, abuffer solenoid valve, a buffer tank and a drain solenoid valve. Thesteam trap can collect water from wet hydrogen. The buffer tank is ahollow cavity structure such as a tank.

Preferably, the steam trap has an upper cover, a main body, a lowercover and a filter. The upper cover has a wet hydrogen inlet, a pressuresensor, a dry hydrogen outlet and a temperature sensor. The lower coverhas a liquid storage cavity and a filter support part. The filter has afilter filler and a filter intake channel.

Preferably, the wet hydrogen inlet communicates with the filter airinlet channel. The shape of the filter conforms to the steam traphousing and is mounted inside the steam trap housing. The filter forms agas-liquid separation channel with the steam trap main body. The filterhas a dry air channel that communicates to the upper cover of the steamtrap. The filter forms a liquid channel with the filter support part ofthe lower cover of the steam trap. The upper part of the gas-liquidseparation channel communicates with the dry hydrogen outlet through thedry gas channel. An electronic control system controls the buffersolenoid valve and the drain solenoid valve. The electronic controlsystem controls flow from the liquid storage cavity through the tail gasoutlet, controls the buffer solenoid valve for flow to the buffer tank,and controls the drain solenoid valve for flow out of the buffer tank.

Preferably, a liquid level sensor is arranged inside the liquid storagecavity, which can detect the liquid storage height in real time. Thebuffer tank and steam trap body are preferably cylindrical, rectangularor conical.

Preferably, the width of the gas-liquid separation channel is 3-10 mm,and the depth of the liquid storage chamber is 10-50 mm. In anyparticular design, it can be matched according to the fuel cell stackpower and the discharge cycle calculation period.

Preferably, the materials of the filler include metal filler, plasticfiller and ceramic filler. The forms of the fillers include filamentousfillers, mesh fillers, laminated fillers and granular fillers. Thepressure sensor can be integrated into the buffer tank. The ceramicfiller can be a porous ceramic honeycomb commonly used for catalyticconversion of combustible exhaust for example, and the metal filler canbe a series of nested metal mesh cups that the wet hydrogen passesthrough. A honeycomb structure may have elongated honeycomb channelsthat are internally disposed within a ceramic structure.

Preferably, the buffer solenoid valve and the drain solenoid valve arecontrolled synchronously or asynchronously with an electronic controlsystem. The electronic control system can first open the buffer solenoidvalve, and then after the buffer tank pressure is balanced with thepressure of the liquid storage chamber or the interval of 0.5-10seconds, the buffer solenoid valve is closed and then the dischargesolenoid valve is opened. When asynchronously controlled a delay can beintroduced so that after an interval of 0.5-10 seconds or when thebuffer tank pressure is consistent with the external pressure, the drainsolenoid valve is closed to achieve asynchronous drainage. Theelectronic control system can select between synchronous andasynchronous drainage depending upon the flow of wet hydrogen.

A fuel cell system thus may include this hydrogen exhaust device.

DESCRIPTION OF FIGURES

FIG. 1 is the diagram of the sole embodiment of the present invention.

FIG. 2 is the outline structure diagram of the steam trap.

FIG. 3 is the diagram of the internal structure of the steam trap.

FIG. 4 is the diagram of the bottom shell of the steam trap.

FIG. 5 is the structure diagram of the filter support part.

The following callout list of elements can be a useful guide inreferencing the element numbers of the figures.

1 Steam Trap 2 Buffer Solenoid Valve 3 Buffer Tank 4 Drain SolenoidValve 5 Upper Cover Of Steam Trap 6 Main Body Of Steam Trap 7 LowerCover Of Steam Trap 8 Wet Hydrogen Inlet 9 Pressure Sensor 10 DryHydrogen Outlet 11 Temperature Sensor 12 Tail Gas Outlet 13 Filter 14Filter Packing 15 Air Inlet Channel Of Filter 16 Gas-Liquid SeparationChannel 17 Dry Gas Channel 18 Liquid Channel 19 Liquid Storage Chamber20 Filter Support 21 Liquid Level Sensor 22 Lower Flange 23 Lower OutletNipple 24 Upper Flange 26 Lower Flange Connector 27 Upper FlangeConnector 28 Upper Flange Connector Indent 29 Lower Flange ConnectorIndent 31 Buffer Solenoid Upper Housing 32 Buffer Solenoid More Housing33 Buffer Solenoid Valve Intake Connection 34 Buffer Solenoid ValveOutlet Connection 41 Buffer Tank Upper Inlet 42 Buffer Tank Lower Outlet43 Buffer Tank Outlet 51 Drain Solenoid Valve Upper Housing 52 DrainSolenoid Lower Housing 53 Drain Solenoid Valve Intake Connection 54Drain Solenoid Valve Outlet Connection 61 Wet Hydrogen Flow 62 DryingHydrogen Flow 63 Dry Hydrogen 64 Drip 65 Liquid 88 Electronic ControlSystem

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As seen in FIGS. 1-2 , the steam trap 1 has a housing formed as athree-part body. An upper flange 24 connects the steam trap upper cover5 to a steam trap main body 6. The steam trap 1 also has a lower flange22 that connects a steam trap main body 6 to a steam trap lower cover 7.The upper flange is formed between the steam trap upper cover at a steamtrap upper cover flange and a steam trap main body upper flange thatmeet together to form the upper flange. The upper flange has one or moreupper flange connectors 27 recessed in upper flange connector indents28. Similarly, the steam trap lower cover 7 has a steam trap lower coverflange that meets with the steam trap main body lower flange to form thelower flange. Similarly, the lower flange connector 26 is mounted in alower flange connector indent 29 formed on a steam trap lower cover 7.The tail gas outlet 12 is mounted on the steam trap lower cover 7. Thewet hydrogen inlet 8 and dry hydrogen outlet 10 are mounted to the steamtrap upper cover 5. The pressure sensor 9 and the temperature sensor 11are also mounted to the steam trap upper cover 5.

The tail gas outlet 12 extends from a lower portion of the steam traplower cover 7 and has a lower outlet nipple 23 that connects to a buffersolenoid valve intake connection 33. The buffer solenoid valve 2 has abuffer solenoid upper housing 31 and a buffer solenoid lower housing 32.The buffer solenoid lower housing contains the mechanical valve of thebuffer solenoid valve, and the buffer solenoid upper housing 31 containsthe solenoid coil and solenoid for actuating the mechanical valve of thebuffer solenoid valve. The buffer solenoid lower housing 32 has a buffersolenoid valve intake connection 33 in communication with the buffersolenoid valve outlet connection 34 when the buffer solenoid valve 2 isin the disengaged position. When the buffer solenoid valve 2 is in theengaged position, the buffer solenoid valve intake connection 33 isstopped which retains fluid in the water reservoir of the steam traplower cover 7.

The buffer solenoid valve outlet connection 34 connects to the buffertank upper inlet 41 of the buffer tank 3. The buffer tank 3 also has abuffer tank outlet 43 and the buffer tank outlet 43 has a buffer tank alower outlet 42 which connects to the drain solenoid valve 4 at a drainsolenoid valve intake connection 53. The drain solenoid valve 4 has adrain solenoid valve upper housing 51 and a drain solenoid lower housing52. The drain solenoid lower housing 52 contains a drain solenoidwarehousing mechanical valve that allows fluid communication between thedrain solenoid valve intake connection 53 and the drain solenoid valveoutlet connection 54 when the drain solenoid valve 4 is in disengagedposition. When the drain solenoid valve 4 is in an engaged position, thedrain solenoid valve intake connection 53 is stopped which retains fluidin the buffer tank 3. The drain solenoid valve upper housing 51 containsthe solenoid and solenoid coil of the drain solenoid valve 4 with thesolenoid mechanically engaged to control the mechanical valve of thedrain solenoid.

As seen in FIG. 3 , the pressure sensor 9 is mounted near the wethydrogen inlet 8 so that the pressure sensor 9 can sense the intakepressure. The temperature sensor 11 is mounted near the dry hydrogenoutlet 10 which provides a temperature reading of the dry hydrogen 63exiting the exhaust system. The dry hydrogen 63 can exit the dryhydrogen outlet 10 and recycled as additional fuel. The wet hydrogen 61entering the wet hydrogen inlet 8 enters a dry gas channel 17 and agas-liquid separation channel 16. The flow of wet hydrogen passesthrough the filter packing 14 of the filter 13 and a liquid channel 18formed at a lower portion of the filter 13 allows drip 64 of watercondensed on the possibly honeycomb structure 66 of the filter packing14 to jet down to a liquid storage chamber 19 where a pool of liquid 65accumulates. When the pool of liquid 65 accumulates to reach a level ofthe liquid level sensor 21, the electronic control system 88 isconfigured to flush the liquid 65 out through the tail gas outlet 12 byopening the buffer solenoid valve 2. The flushed liquid that enters thebuffer tank 3 awaits drainage through the drain solenoid valve 4.

As the wet hydrogen 61 passes through the filter 13, the wet hydrogen 61becomes drying hydrogen 62 which is in the process of drying as thesteam or water exits the hydrogen and is no longer entrained within thehydrogen. The drying hydrogen 62 becomes a flow of dry hydrogen 63 whichexits the dry hydrogen outlet 10. The temperature sensor 11 takes thetemperature of the dry hydrogen 63 when the dry hydrogen 63 is exitingthe dry hydrogen outlet 10 at the steam trap upper cover. The filter 16is held by a filter support 20 and a filter air inlet channel 15 formedaxially through the filter 13 provides an air channel to collect the dryhydrogen 63.

Thus, the steam trap collects liquid and the combination of the buffersolenoid valve and the drain solenoid valve provides a controlled andstaged release of fluid from the steam trap lower cover 7. The pressurewithin the steam trap 1 is greater than the pressure of the buffer tank3 so that the expulsion from the buffer tank 3 can be performed usingthe pressure of the steam trap 1.

As seen in FIGS. 4-5 , the trail gas outlet 12 extends laterally awayfrom the filter 13. The filter support 20 can be a bracket thatcircumscribes the filter 13 and holds it as a cage support structure.The filter support may have liquid channels 18 for allowing drainage ofwater along the sides of the filter 13. The filter 13 may have acylindrical shape with a rounded sidewall allowing dripping water toflow downwardly by gravity to the liquid storage chamber 19.

In a timed mode of the hydrogen exhaust device for a fuel cell and afuel cell system employing the device, the system power can be at 80 kw.The main body of the steam trap and buffer tank of the device can becylindrical. The width of the gas-liquid separation channel is 4 mm, andthe depth of the liquid storage chamber is 15 mm. The material of thefilter filler includes the metal filler, and the form of filler includesfilamentous filler. The liquid level sensor is not seated in the liquidstorage chamber of the steam trap, or not connected to the electroniccontrol unit. A pressure sensor is not integrated in the buffer tank, ornot connected to the electronic control unit. The buffer solenoid valveand the drain solenoid valve are asynchronously controlled at a 2-secondinterval during operation. The electronic control unit first opens thebuffer solenoid valve, then closes the buffer solenoid valve after 2seconds, then opens the drain solenoid valve. Afterwards, the electroniccontrol unit closes the drain solenoid valve after 2 seconds and opensthe buffer solenoid valve to achieve asynchronous draining.

In an automatic mode the liquid level sensor of the liquid storagecavity and the pressure sensor of the buffer tank are added or connectedto the electronic control unit. Automatic drainage by pressure balanceis adopted during operation, such that whenever the liquid level sensorreaches the drain position, the electronic control unit is configured tofirst open the buffer solenoid valve. After the pressure of the buffertank is balanced with the pressure of the liquid storage chamber, thebuffer solenoid valve is closed, and then the drainage solenoid valve isopened. After the buffer tank pressure equalizes relative to externalpressure, the discharge solenoid valve is closed to realize automaticasynchronous discharge.

The following advantages of the present invention include the following:

The anode side of a fuel-cell system generates a flow of wet hydrogengas which can be collected and then received in a buffer tank. The waterand waste gas in the buffer tank are discharged to the outside through adrain solenoid valve. The buffering of the buffer tank reduces thepressure fluctuation during direct discharge, which is conducive toimproving the operating stability of the system and prolonging theservice life of the fuel cell system.

The exhaust system integrates drainage, exhaust, temperature, pressureand liquid volume collection by steam trap, which reduces the complexityof a fuel cell system design.

The filter conforms to the steam trap housing, and the gas-liquidseparation channel is formed with the main body of the steam traphousing. The filter forms a dry gas channel with the upper cover of thesteam trap, and forms a liquid channel with the filter support part ofthe lower cover of the steam trap. Each channel is formed through thecoupling of components, which does not need additional which improvesconstruction simplicity.

The exhaust system can operate in synchronous or asynchronous modethrough the buffer solenoid valve, drain solenoid valve. At the sametime, the liquid level sensor allows automatic liquid discharge toensure smooth system operation.

The modular design of the steam trap housing allows different sizedupper covers and lower covers to work with the same steam trap main bodyto allow modular modification when sizing to different fuel cell systemsor operating conditions.

The sole embodiment of the present invention as described in thespecification also encompasses the best mode of the present invention.

1. A hydrogen fuel cell exhaust system comprising: a. a steam trap,wherein the steam trap is configured to collect water from a flow of wethydrogen, wherein the steam trap includes a steam trap housing; b. atail gas outlet formed on the steam trap; c. a buffer solenoid valveconnected to the tail gas outlet; d. a buffer tank connected to thebuffer solenoid, wherein the buffer tank has a hollow cavity structure;and e. a drain solenoid valve connected to the buffer tank.
 2. Thehydrogen fuel cell exhaust system of claim 1, wherein the steam trapfurther includes an upper cover, a main body, a lower cover and afilter.
 3. The hydrogen fuel cell exhaust system of claim 2, wherein theupper cover has a wet hydrogen inlet and a pressure sensor at the wethydrogen inlet, wherein the upper cover also has a dry hydrogen outletand a temperature sensor at the dry hydrogen outlet.
 4. The hydrogenfuel cell exhaust system of claim 3, wherein the lower cover has aliquid storage cavity and a filter support part, a filter filler and afilter intake channel.
 5. The hydrogen fuel cell exhaust system of claim3, wherein the wet hydrogen inlet communicates with the filter air inletchannel.
 6. The hydrogen fuel cell exhaust system of claim 3, wherein afilter shape conforms to the steam trap housing and is mounted insidethe steam trap housing, and wherein the filter forms a gas-liquidseparation channel with the main body of the steam trap and wherein thefilter has a dry air channel that communicates to the upper cover of thesteam trap.
 7. The hydrogen fuel cell exhaust system of claim 3, whereinthe filter forms a liquid channel with a filter support part mounted inthe lower cover of the steam trap.
 8. The hydrogen fuel cell exhaustsystem of claim 3, wherein the upper part of the gas-liquid separationchannel communicates with the dry hydrogen outlet through the dry gaschannel.
 9. The hydrogen fuel cell exhaust system of claim 3, whereinthe lower part of the gas-liquid separation channel communicates withthe liquid storage cavity through the liquid channel.
 10. The hydrogenfuel cell exhaust system of claim 3, wherein the lower cover has aliquid storage cavity and a filter support part, a filter filler and afilter intake channel, wherein the wet hydrogen inlet communicates withthe filter air inlet channel, wherein a filter shape conforms to thesteam trap housing and is mounted inside the steam trap housing, whereinthe filter forms a gas-liquid separation channel with the main body ofthe steam trap, wherein the filter has a dry air channel thatcommunicates to the upper cover of the steam trap, wherein the filterforms a liquid channel with a filter support part mounted in the lowercover of the steam trap, wherein the upper part of the gas-liquidseparation channel communicates with the dry hydrogen outlet through thedry gas channel, wherein the lower part of the gas-liquid separationchannel communicates with the liquid storage cavity through the liquidchannel.
 11. The hydrogen fuel cell exhaust system of claim 10, furthercomprising a liquid level sensor arranged inside the liquid storagecavity, wherein the liquid level sensor is configured to detect theliquid storage height in real time.
 12. The hydrogen fuel cell exhaustsystem of claim 10, wherein a width of the gas-liquid separation channelis 3-10 mm, and a depth of the liquid storage chamber is 10-50 mm. 13.The hydrogen fuel cell exhaust system of claim 10, wherein the materialsof the filler are selected from the group of a metal filler, plasticfiller and ceramic filler.
 14. The hydrogen fuel cell exhaust system ofclaim 10, wherein a form of the fillers is selected from the group offilamentous fillers, mesh fillers, laminated fillers and granularfillers.
 15. The hydrogen fuel cell exhaust system of claim 10, whereinthe pressure sensor is integrated into the buffer tank.
 16. The hydrogenfuel cell exhaust system of claim 10, wherein the is a porous ceramichoneycomb.
 17. The hydrogen fuel cell exhaust system of claim 10,further including an electronic control system that controls the buffersolenoid valve and the drain solenoid valve, wherein the electroniccontrol system controls flow from the liquid storage cavity through thetail gas outlet, controls the buffer solenoid valve for flow to thebuffer tank, and controls the drain solenoid valve for flow out of thebuffer tank.
 18. The hydrogen fuel cell exhaust system of claim 17,wherein the electronic control system controls the buffer solenoid valveand the drain solenoid valve in a synchronous mode and an asynchronousmode, wherein the electronic control system can select between theasynchronous mode and the synchronous mode.
 19. The hydrogen fuel cellexhaust system of claim 17, wherein the electronic control system has anasynchronous mode that first opens the buffer solenoid valve, and thenafter a buffer tank pressure is balanced with the pressure of the liquidstorage chamber or a time interval of 0.5-10 seconds elapses, then thebuffer solenoid valve is closed and then the discharge solenoid valve isopened, wherein a delay is introduced so that after an interval of0.5-10 seconds or when the buffer tank pressure is consistent with theexternal pressure, the drain solenoid valve is closed to achieveasynchronous drainage.
 20. The hydrogen fuel cell exhaust system ofclaim 17, wherein the electronic control system is configured toautomatically select between a synchronous mode and an asynchronous modedepending upon a flow of wet hydrogen as measured by a pressure sensormounted near the flow of wet hydrogen at a wet hydrogen intake of thesteam trap.